In the past, there have been numerous attempts to make couplings that connect tubes to various fittings. For example, there are couplings that have an end press fitted into either the elbow or the diverter while the other end of the coupling, that connects to the tube, has a barbed nipple and a male threaded portion in conjunction with a nut N to secure the tube to the coupling.
Other couplings employ a threaded end, which screws into the diverter or the elbow, and a barbed nipple to secure the tube to the coupling.
The couplings used in the past that only employ a barbed nipple to connect to the tube have failed to provide the necessary securing of the tube. Namely, when the fluid pressure within the tube line increases, the tube will slip off the barbed nipple and cause system failure.
With regard to the couplings employing an end that is press fitted into other fittings, there have been numerous problems. For example, when a diverter malfunctions, or breaks, one cannot simply replace the diverter, but rather both the diverter and the coupling must be replaced. One must replace both because the coupling cannot be removed from the diverter, since they are press fitted together. An additional problem is that the "O" ring that seals the coupling to the diverter cannot be replaced, nor can the spring within the diverter be replaced or cleaned. Another problem that has developed with the press fit couplings is the flaking-off of any plating contained on the coupling. The flaking occurs because oil seeps out from the material of the coupling. When the coupling is being machined, oil is used to reduce the heat and to facilitate the machining. After machining, the coupling is cleaned off; however, minute amounts of oil remain in the material. Subsequent to machining, the coupling is plated with a anti-corrosion material. When the coupling is press fitted to the other fittings, such as the diverter or the elbow, the pressure exerted on the press fitted portion of the coupling causes the minute amounts of oil to seep from the coupling. This seepage forming under the plating causes the plating to flake off. The hazard is that the flakes can then pass into the fluid-line and anti-corrosion efforts are lost.
In and above these shortcomings, the previous couplings have also failed to provide an easy and efficient way to install, remove, tighten or loosen the coupling to and from other fittings. To tighten or loosen any of the previous couplings, it is likely that one would either damage necessary threads or damage or collapse the thin nipple by using some wrenching tool, like vice grips.
These attempts have not all succeeded in providing: the necessary securing of the tube to the coupling; the ability to be able to replace the diverter elbow or coupling; or, an easy and efficient way to install, remove, tighten or loosen the coupling.